The present invention relates in general terms to clutch release devices, particularly for motor vehicles.
The term clutch release device used herein is intended to refer to the whole assembly made up by a clutch release bearing and the clutch release yoke or fork adapted to act on it.
In known constructions, the clutch release bearing designed to act on the clutch shift device of a clutch assembly generally consists of an actuating part which acts on the clutch shift device, and an operating part on which the clutch release yoke operates, the actuating part being axially coupled to the operating part, and the operating part including transversely, a flange on which the clutch release yoke acts, this flange optionally being split up into at least two radial arms.
In addition, the clutch release yoke generally includes a region of articulation at which it is adapted to be pivotally operated under the control of a control arm, and an active region or operating portion by means of which it is adapted to act on the clutch release bearing.
The control arm of such a clutch release yoke may for example, be part of the same body as the active region. It would have been manufactured as a one piece structure together with the latter, and, this generally is the case when its support is a ball joint.
Alternatively, the control arm of the clutch release yoke may consist of a part which is separate from the active region and this in practice is the case when its support is constituted by a pivoting shaft. The control arm and active region in this case are able to be mutually spaced from each other along this pivoting shaft and the control arm may even, individually, extend with respect to the shaft at an angular orientation which differs from that of the active region.
Whatever the case may be, the control arm of the clutch release yoke is intended to be linked by a transmission system to a clutch pedal. The active region is adapted to act on the associated clutch release bearing at two points of abutment or contact points which are substantially located at diametrically opposed positions with respect to each other in an axial plane of the clutch release bearing.
At the present time, the points of abutment which are thus present on the clutch release yoke are generally each formed at the respective end of two fingers provided at its active region, so that the latter generally has a U-shaped configuration. The active region is connected at its mid portion to the remainder of the clutch release yoke.
Stated in other terms, because of the opening formed by the gap between these two arms, the active region of the clutch release yoke is open in a direction which, generally, is totally contained within the plane. The plane is perpendicular to the axis about which the clutch release yoke pivots during its operation, and for the sake of simplicity, will be referred to as the plane of pivoting of the clutch release yoke.
In addition, the axial plane of action of the clutch release yoke, which contains its points of abutment is consequently usually perpendicular to its plane of pivoting.
The present invention particularly but not exclusively, concerns the case where the clutch release bearing to be operated is a "pulled" clutch release bearing. A pulled release bearing is one designed to exercise traction on the clutch shift device of the respective clutch mechanism, and has a portion of its actuating part engaged behind said clutch shift device.
In the case of "pulled" clutch release bearings, the flange of the operating part on which the clutch release yoke is designed to act is usually set at a distance from the actuating part, in order for the active region of the clutch release yoke to be able to perform traction on this flange. In other words on the side of the latter which is directed towards the actuating path.
One of the problems to be resolved when assembling such "pulled" clutch release bearings results from the fact that an assembly of this type requires relative engagement of the clutch release bearing and the clutch release yoke. The active region of the clutch release yoke is required to be engaged transversely between, first, the flange provided to allow its operation, on the operating part of the clutch release bearing and, second, the actuating part of the latter.
Stated in other terms, the active region of the clutch release yoke must be engaged behind the transverse flange of the operating part of the clutch release bearing.
Now, as we are here dealing with a "pulled" clutch release bearing, the latter is carried by the actual clutch mechanism with a portion of its actuating part engaged behind the clutch shift device of the latter while the clutch release yoke is, in an independent fashion, usually carried by the housing of a gearbox and being, at its region of articulation, pivotally mounted about a fixed support which can be a transverse shaft or a ball joint, which itself is carried on the housing.
It is consequently necessary when bringing this gearbox housing and the actual clutch, which is usually carried by the housing of the corresponding engine, together in the axial sense, to progressively engage the active region of the clutch release yoke behind the transverse flange of the operating part of the clutch release bearing.
This operation, implying as it does that the clutch release yoke be initially presented substantially flat and lying in a horizontal position and then, by pivoting the clutch release yoke it is progressively returned to the vertical position with the active region gradually becoming engaged behind the transverse flange of the operating part of the clutch release bearing. It is difficult to carry this out in practice, particularly when the clutch release yoke is pivotally mounted on a ball joint.
Moreover, this operation may turn out to be impossible as the pivoting of the clutch release yoke which is necessary to return it to its position requires a significant amount of dead space, which is not always available.
In order to overcome this difficulty, it has been proposed to position the clutch release bearing onto the clutch release yoke before the clutch release bearing is mounted onto the clutch shift device of the clutch concerned, and then, at the time, when the housings of the gearbox and clutch are being brought together, to provide for automatic engagement, under blind conditions, of the clutch release bearing with the clutch shift device of the clutch mechanism.
However, the corresponding provisions for engagement do not readily lend themselves to possible subsequent dis-assembly.
It has also been proposed to engage the clutch release yoke with the clutch release bearing in the transverse sense after the gearbox and clutch housing have been brought together in the axial sense, and consequently, without the prior assembly of this clutch release yoke onto the gearbox and clutch housing.
But, in practice, such a solution is only acceptable when the support for the clutch release yoke on the gearbox housing is external of the latter.
If the support is a ball joint, which is located inside the gearbox housing then it is necessary to provide in the clutch release yoke and in the region of the housing an opening which is suitable for an engagement of this type and usually has a negative effect on the mechanical strength of the clutch release yoke.
It has been proposed, finally, to carry out the assembly by using a pivoting action, of the bayonet or quarter turn type, of the clutch release bearing with respect to the clutch release yoke.
But, in practice, such a solution is only readily applicable to vehicles in which there is easy access to the gearbox housing.
In the case of private passenger vehicles, the necessary space is, on the contrary, not always available.
The present invention, stated in general terms, has the object of providing an arrangement which, while avoiding these disadvantages, makes it possible to overcome the difficulties listed above in a very simple manner.